etting and plaster, or expanded metal laths and plaster, or wired glass in proper frames. The floors should be of fireproot brick or tiles or cement.

NOTES.—Any hollow space, whether in cornice, wall, floor. partition or any other part of the constructional part of a building, presents an increased hazard, as it forms a possible lodgment place for inflammable and spontaneously combustible materials, is a concealed space in which a fire may develop to a very great extent before it is discovered, and is usually a draft. hole which would contribute to the rapid and non-preventable spread of a fire; hence it is of the greatest importance that these hollow spaces should be obviated in construction, done away with wherever found, or so divided up by fireproof partitions as to make the concealed space of as limited an area as possible.

All holes in floors, whether cracks, worn places, spaces around columns, loosely fitting flooring, either between the floor boards or at the walls, should be repaired so that the flooring is tight; this is especially necessary in "hollow construction," as here the liability of papers, matches, lighted cigars and cigarettes, inflammable and spontaneously combustible rubbish and materials falling through the openings in the floors into the concealed spaces below is a very decided and greatly increased hazard.

CLOSETS. These constitute concealed spaces, and, therefore, attention should be given to their construction. Wooden tops are not desirable; a top of paper will keep out the dust and should be used instead of wood; the doors should be provided with glass, so that the interior of the closet is always in view Closets for workingmen's clothes should have wire-netted doors. PARTITIONS.-Wooden studding, lath and plaster, or wood ceiled partitions simply add more concealed spaces in a building, and are very objectionable and should be removed wherever possible. Two-inch tongue and groove or splined planking, well set up, makes a good solid partition and presents a surface which offers resistance to fire. Fireproof bricks and tiles make the most desirable partitions. If a wooden studding is to be built it should be wire-netted or provided with expanded wire laths and the plaster put on the netting or metal laths.

Where openings in walls or partitions for light are necessary, and where without these openings the walls would be fire walls

or the partitions would be solid, wired glass can be used to great advantage. The minimum thickness for the glass is one-quarterinch (full) if rough plate, ribbed or figured, and no polished glass less than 5-16 inch can be used (this 5-16 inch to be the thickness after the glass is polished); the maximum mesh of the wire is I inch, and it must not be smaller than No. 22 B. & S. wire gauge. This glass must be set in suitable frames, hollow metallic or wrought iron, and no vent spaces must be left around the frames of the glass. Prism glass, in which the glass units do not exceed 4 inches in either direction, and are of a minimum thickness of 3-16 inch, when set in proper frames can be used in special cases.

SHAFT OPENINGS IN FIRE WALLS.-Should be protected by fire-doors made of two thicknesses of 8-inch narrow, matched, thoroughly seasoned boards, put together at right angles and securely nailed with wrought iron clinch nails and covered with heavy tin plates, locked joints, nailed under the seams, as per specifications for standard tin clad fire doors, and be hinged to a single stud bolt in wall, and retained at bottom by proper reverse angle, securely bolted to the wall. (National Board of Fire Underwriters.)

BELT OPENINGS THROUGH WALLS.-Should be protected by double fire doors or metal hood.

Double doors should be made of the same thickness and in the same manner as standard tin clad fire doors, and arranged so as to slide in upper and lower guard rails or channels. which shall retain them in place; these channels to be made of 24x24x4-inch angle irons securely riveted together and secured by 3/4-inch bolts through the walls. Z bars of proper dimensions may be used if obtainable. Channels to be long enough to retain doors when open. Doors to be provided with suitable hooks and staples for holding them closed.

Metal hood made of heavy galvanized iron, in such a form as to completely cover the belt, and the pulley over which it runs should be securely fastened to the wall around the belt hole. No solder must be used in the construction. Metal hoods are inferior to double doors and should be used only when the doors are not practicable. (National Board of Fire Underwriters.) WIRED GLASS for SKYLIGHTS is strongly advised.

Where openings are not seriously exposed wired glass set in suitable frames or wired glass shutters can be used in place of fire shutters. For the purpose of retarding the spread of fire wired glass is more efficient than prism glass.

BRIDGE TRUSSES.-Where long bridge trusses are used to support roofs the walls on which the trusses rest should be carefully inspected as to their strength, and where they are seemingly inadequate for the weight carried, with an additional weight of outside foreign material (as burning timbers, etc., in case of fire in exposures), the trusses should be supported by independent posts running from the ground up.

PAINTING SHEET METALS.-Exposed sheet metal (metal roofs, sides, etc.) should always be painted. Iron oxide paints are the best for metal as they adhere more firmly than lead paints.

Wherever possible iron posts should be protected against heat by covering them with fireproof brick or tiles, or wire netting, or expanded metal laths, the netting and laths being covered with plaster.

The bright tin of fire shutters and doors should be given a coat of asphaltum before being painted, and the paint put on should preferably be of a light color.

FIRE-RETARDING PAINTS.-Whitewash made of lime and water with a quantity of salt added is the best fire retardant of this character. Frequent coating is necessary, as the dried whitewash flakes and peels off. Cement-wash, made of hydraulic cement and water, is a very good wash and more lasting than whitewash. The various paints known as "fireproof," are more or less fire retardants, but must be carefully applied; where placed upon non-porous materials they are apt to lose their effectiveness by peeling off. Oxide of iron paints are the best for metals.

FIRE-RETARDING COATINGS.-Thin board partitions and uneven surfaces can best be treated by covering them with sheet asbestos, and placing over this a covering of lock-jointed tin. There are various other materials, such as air-cell fireboard, plaster board, plastered wire netting, but all must be properly laid on to be effective, the primary point being the exclusion of air between the covered wood and the covering.

Fireproofed wood is not as yet a commercial commodity, and has not yet reached a point where it can be generally used in an economical way.

Oil, shellac and varnish finish are not recommended on account of the increase of inflammable material in the building.

The height of a building, under public fire protection, should be governed by the height to which the fire department can throw a good 1%-inch fire stream, as buildings in excess of this height would lack proper protection in case of fire.

MORTARS-CEMENT MORTAR.-A mortar in the proportion of three parts of sand to one of cement, when applied immediately upon mixing, makes a strong and binding mortar. Lime mortar should be made of four parts of sand to one of lime, and should not be used until thoroughly slaked. Cement and lime mortar should be one part of cement, one part of lime and three parts of sand. All of these proportions can be varied for different classes of work, but are good bases for mixtures.

Wooden laths should be removed wherever possible, as should all furring and wooden sheathing.

There should be as few openings as possible in any walls. The basis for area rate, universal schedule, is 2,500 square feet.

CHAPTER III.

FIRE DOORS AND SHUTTERS.

There are a great many "so-called" fire doors and shutters, often on very important openings, which, when exposed to only a relatively low degree of heat, would prove to be entirely worthless. They may be of iron, whether heavy or light, which will warp and bend and practically uncover the opening, when exposed to heat, or be of wood covered with iron (corrugated, galvanized, etc.), which will buckle and bend and pull the nails out and thus leave the wood exposed, or be improperly covered with tin. Hangings are apt to be of poor quality and improperly placed, and fastenings are not of proper strength or construction, and in numerous other particulars the doors and shutters are weak and practically worthless.

There is only one kind of fire door and shutters that is of such a character as to be of real value and dependence, and that is the standard tin clad.

STANDARD TIN CLAD FIRE DOORS (National Board of Fire Underwriters).—The woodwork should be of sound, well seasoned white pine or similar non-resinous wood, dressed, tongued and grooved boards, not over 6 inches in width, and when there is a door on one side only of an opening the thickness of the wood should be at least 21⁄2 inches; where the wood is 2 inches thick there should be two layers of 1-inch boards, one laid vertically and the other diagonally or at right angles; where the wood is 21⁄2 inches thick there should be three equal thicknesses of boards, the outside layers being vertical and the inner layer horizontal. The layers to be securely fastened together by wrought iron clinch nails, driven in flush and clinched, so as to leave smooth surfaces on both sides of the door.

Tin Covering.-Tin plate to be 14x20 inches, "IC" charcoal, 108 pounds to the box. The corners should be covered first, a whole sheet of tin being used without cutting, making a mitre fold with it. The edges should next be covered, the tin